Because of the decreased venous compliance in hypertensive dialysis patients, it was investigated whether their venous system exhibited structural abnormalities. Venous samples were taken during transplantation from the common and external iliac vein in 12 hypertensive and 6 normotensive uremic patients and from the distal inferior caval vein and the common iliac vein in 7 kidney donors and 5 autopsy patients without history of cardiovascular disease. The thickness of the venous media was significantly increased in hypertensive uremic patients as compared to controls, but did not differ between normotensive patients and controls. The quantity of medial collagen did not differ among the various groups. The smooth muscle content of the media was increased in 5 uremic patients (2 normotensive and 3 hypertensive patients), whereas almost no smooth muscle was observed in the media of controls. Intimal thickening was observed neither in uremic patients nor in controls.
In conclusion: increased medial thickness in hypertensive dialysis patients could be an explanation for the decreased venous compliance previously found in these patients.